Fluid fuel burning heater



June 19, 1934. s. A/MOSS ET AL FLUID FUEL BURNING HEATER Filed March 20, 1931 K m H Li? mAP md m erQMN A VAWUP P im Q h 55 T Patented June 19, 1934 UNITED STATES PATENT OFFICE FLUID FUEL BURNING HEATER New -York Application March 20, 1931, Serial No. 524,104

3 Claims.

Our invention relates to fluid fuel burning heaters such as oil burning heaters adapted for residence or building heating service or for furnaces in industrial plants.

In such service the roaring noise, soot and smoke usually produced in the combustion of oil are most undesirable. Thus with the ordinary type of oil burner, the oil is burned in an excess of combustion air in an endeavor to obtain complete combustion of all particles of the oil. A flickering or pulsating flame of a yellow color is produced due to the tendency of the oil to crack, leaving the less volatile constituents partially unconsumed in the process of combustion. Such combustion produces not only low heating efficiency but also more or less noise, smoke and soot depending upon how successfully the consumption of the less volatile constituents is carried out.

It is, therefore, one of the principal objects of the invention to provide an oil burning heater in which the combustion is practically noiseless and is of such improved quality as to eliminate substantially all soot and smoke and provide the maximum heating efficiency.

In accordance with the present invention a materially improved process of combustion is obtained. There is no yellow flame produced but rather a transparent and formless combustion fog or haze of an orange-purple color, or with some proportions of air and oil, a transparent body of products of combustion. The combustion is so complete in the fog or haze that a flue gas analysis shows no CO content and very little excess 0 in the products of combustion.

Briefly, to produce combustion by means of the process known as hydroxylation and thus prevent the formation of soot, it is necessary that the hydro-carbons and combustion air be preheated and that time be allowed for the entrance of oxygen into the hydro-carbon molecules. In our invention the oil and combustion air are supplied to the combustion chamber having the proper relative proportions for complete combustion. This oil and air is projected preferably, but not necessarily, in a downwardly directed stream at a speed in excess of the rate of propagation of flame, through the products of complete and partial combustion toward a highly heated permeable refractory mass. The fuel is directed downwardly at the center of what might be termed a cone of combustion air. At the nozzle the fuel and air are poorly mixed so that combustion can not take place at the nozzle. As the fuel and air move downwardly through the prodnets of complete and partial combustion towards the permeable refractory mass, both the fuel and air are preheated and no combustion takes place between the nozzle and the refractory bed which action permits or allows time sufiicient for the entrance of the oxygen into the hydro-carbons to form a hydroxylated mixture. The distance between the nozzle and refractory bed is such as to allow sufficient time for hydroxylation to take place. As the air and fuel penetrate into the heated permeable refractory mass the velocity is reduced, the oil and air thoroughly mixed and gasified becomes ignited and is all or nearly all burned. The oncoming stream, however, quickly forces the gasified burning mixture and products of combustion from the refractory mass to form the fog or haze in the combustion chamber where the combustion is completed. The switfly moving stream of oil and air entering this oppositely moving body of products of partial and complete combustion and combustion fog or haze is subjected to the heat radiated therefrom as well as from the heated refractory mass and produces a turbulence in the.body surrounding the air and oil mixture stream. Thus a portion of the surrounding body is entrained and carried along by the ,swiftly moving air and oil stream which thus assists in preheating the oil and air to assist in the hydroxylation process. Withthe proper proportioning of the combustion chamber, the refractory mass and the inlet and outlet passages of the combustion chamber, the whole process is entirely noiseless with a marked absence of any roaring or pulsations.

By varying the amount of air and oil supplied, the density of the combustion fog or haze can be varied throughout a wide range, the combus-l tion fog or haze, and the products of combustion, however, at all times filling the combustion chamber adjacent the refractory mass.

The present invention also provides a simple form of apparatus for supplying the swiftly moving stream of air and oil arranged so that the proper relative amounts of air and oil are main tained to produce the variation in density of the combustion fog or haze.

The invention may be better understood from the accompanying drawing in which the single figure schematically illustrates a domestic oil burner embodying the improvements of the present invention.

In the drawing the combustion chamber 10 of a domestic steam or hot water heater 11 is provided substantially opposite the outlet passage 10 for the products of combustion with a permeable refractory mass 12 against which a stream of air and oil 13 and 13' is projected at high velocity from the downwardly directed nozzle 14. It has been found that for best operation the distance across the combustion chamber should be less than three times the distance from the nozzle to the refractory mass, the preferred ratio being as shown in the drawing such that the mean distance across the combustion chamber is substantially the same as the distance between the nozzle and the refractory mass. The air is supplied to the nozzle 14 by the high speed centrifugal blower 15 through the conduit 16. In order to silence pulsations of the blower 15, the air inlet conduit 17 is provided with a mufiler 18. The volume of air supplied is controlled by the valve 19. a

The high speed centrifugal blower 15 is driven by an electric motor 20, the shaft of which is also connected to drive the oil pump 21. The oil pump 21 supplies oil from the storage tank 22 to the closed chamber 23 from which it passes by means of the pipe 24 to the oil outlet orifice 25 in the nozzle 14. The float valve 26 controls the bypass return of the oil from the chamber 23 to the tank 22 so as to maintain a substantially fixed oil level in the chamber 23. An overflow dam could be provided instead of the float for bypassing excess oil. The oil outlet orifice 25 in the nozzle 14 is located centrally with respect to the air outlet and slightly above the level of the oil in chamber 23 thereby effectively preventing discharge of the oil when the burner is notin operation.

In order to cause oil to be discharged at the outlet 25 when the burner is in operation, the pressure created by the centrifugal blower 15 is communicated to the oil in the chamber 23 by means of the conduit 2'7. Thus as soon as the blower 15 is set into operation, the pressure exerted upon the oil through the conduit 27 causes the oil to be discharged at the outlet 25. By adjusting the air control valve 19 the pressure acting on the oil in chamber 23 is varied, in such manner that the flow of oil through the nozzle 25, is directly proportional to the flow of air through the nozzle 14, and therefore the air and oil supply may be controlled simultaneously and in proper proportions to produce the combustion fog or haze in the combustion chamber 10.

In order to initially heat the refractory mass 12, the auxiliary nozzle 30 is provided. Air is supplied to the auxiliary nozzle 30 from the main air line 16 through the conduit 31 under the control of the valve 32. Oil is supplied from the reservoir 23 through the conduit 33 under the control of valve 34. The oil valve 34 and the air valve 32 may be connected to be operated simultaneously by the electromagnet 35 or in any other suitable manner.

The ignition of the air and oil mixture at the auxiliary nozzle 30 may be accomplished by the jump spark electrodes 36 energized from the transformer 37 or by any other suitable means, such as a pilot gas flame, an electric heating coil or the like. The operation of motor 20, electromagnet 35 and the ignition apparatus may be controlled in a suitable manner by the control apparatus 38 in conjunction with a room thermostat 39 and the flame responsive safety relay 40. Since the control, other than of the variable air and oil mixture, forms no part of the present invention, no further detailed description is deemed necessary.

In operation, motor 20 is started to operate the blower 15 and the oil pump 21. The ignition apparatus 36 and 37 is set into operation and the electromagnet 35 is energized to move the valve 32 and valve 34 so as to admit air and oil to the auxiliary nozzle 30. In this way combustion is established at the auxiliary nozzle 30 and continues until the refractory mass 12 is heated. The ignition is then discontinued and the valves 32 and 34 close to cut off the air and oil supply to the auxiliary nozzle 30. However, the air and oil supply from the nozzle 14 is projected at high velocity through the products of complete and partial combustion against the heated refractory mass 12 and maintains coinbustion in the combustion chamber 10 in the manner described above. Since all of the combustion air is supplied through the nozzle 14 in the proper proportion to produce complete combustion of the oil, a maximum heating efiiciency is obtained. The combustion, as previously noted, occurs as a formless, transparent fog or haze substantially filling the combustion chamber 10 above the permeable refractory mass. The products of combustion, after passing through the outlet passage 10' come into contact with the heat abstracting portion 41 of the steam or hot water heater 11, and then are exhausted into the flue pipe 42.

In case the air'and oil mixture supplied from the nozzle 14 produces a combustion resulting in more heat than desired, the valve 19 is operated by crank 43 to reduce the amount of air and hence the amount of oil supplied, thereby varying the density of the combustion fog or haze in the chamber 10.

The crank 43 is arranged to be operated at a very slow speed by a small electric motor located preferably with the control apparatus 38 and connected to crank 43 through speed reducing gearing. The direction of rotation of the motor is controlled by the room thermostat 39 so that in case more heat is desired the valve 19 is operated to increase the supply of air and oil mixture through the nozzle 14. In this way quiet eificient combustion is obtained with a range of oil consumption from one to three units. For example, in a typical domestic heater installation it is possible by adjusting the valve 19 to vary the oil consumption from one gallon per hour to three gallons per hour while maintaining the proper combustion conditions in the chamber 10. This variable combustion feature is a distinct advantage over the usual forms of oil burners which operate satisfactorily with only a substantially fixed rate of oil consumption. Moreover, the increased heating efficiency and the total absence of combustion noise, soot, or smoke distinguish the oil burner of the present invention'from the devices now in use.

What we claim as new and desire to secure by Letters Patent of the United States, is,--

1. An oil burner comprising a combustion chamber having a refractory mass for establishing a zone of combustion therein, an oil pipe extending into the combustion chamber above said mass and having a downwardly directed discharge opening located in opposing spaced relation with the refractory mass to discharge oil downwardly toward said mass, an air pipe surrounding said oil pipe and provided with a. discharge opening surrounding the discharge opening of said oil pipe, an oil reservoir in communication with said oil pipe, means for maintaining the level of the oil in said reservoir a predetermined distance below the level of the discharge opening of said oil pipe,

and a pressure blower communicating with said air pipe and with said reservoir for forcing oil and air into said combustion chamber in substantially proper proportions for combustion.

2. An oil burner comprising a combustion chamber having an outlet for the products of combustion at the top thereof and a bed of permeable refractory material establishing a zone of combustion at the bottom thereof, an oil pipe extending into an intermediate portion of the combustion chamber and having an oil discharge opening disposed in opposing spaced relation with said bed for discharging oil downwardly toward said zone of combustion, an air pipe surrounding said oil pipe and having a discharge opening surrounding said oil discharge opening for directing a column of combustion air around said downwardly discharged oil, an oil reservoir in communication with said oil pipe, means for maintaining the level of the oil in said reservoir a predetermined distance below the level of said oil discharge open-Q ing, a. blower connected to supply air to said air pipe under pressure sufficient to project said column of combustion air at an initial velocity greater than the rate of propagation of flame, a conduit connecting said air pipe and said reservoir for communicating the air pressure to the oil reservoir and thereby force oil to said oil discharge opening, and means for controlling the blower pressure to simultaneously vary the supply of both oil and air to the combustion chamber.

3. An oil burner having in combination, a combustion chamber provided with an outlet for the products of combustion and a refractory mass establishing a. zone of combustion below said outlet, an oil supply pipe extending into said combustion chamber adjacent said outlet and having a downwardly directed discharge opening for discharging a stream of raw oil through the products of combustion toward said zone of combustion for progressively vaporizing said oil as it approaches said zone of combustion, an air supply pipe surrounding said oil pipe and provided with an air discharge opening surrounding said oil discharge opening for enveloping said oil stream with a column of air to progressively mix with said progressively vaporizing oil stream and form a combustible mixture of oil and air at said zone of combustion, a pressure blower connected with said air supply pipe, a valve at the blower intake for regulating the pressure thereof, and means including a pressure equalizing connection between said air supply pipe and said oil supply pipe for proportioning the relative amounts of air and oil for substantially complete combustion.

SANFORD A. MOSS. SAMUEL R. PUFFER. WAVERLEY A. REEVES. 

